This invention relates to security door lock arrangements having incorporated therein a flexible guard element through which the door may be partially opened.
Safety door lock assemblies having a flexible guard chain incorporated therein are already well known as disclosed for example in U.S. Pat. No. 2,946,213 to Reiner. In the foregoing type of security door lock assembly, a manually operable door lock controlled from one side through a knob for example, releases either the lock alone or both the lock and the guard chain through separate operation. A rather complex mechanism is associated with such an arrangement whereby locking of the door is accomplished through a releasable latching mechanism while a separate releasable latching mechanism is associated with the guard chain. Unlocking of the door alone will permit opening of the door to a limited extent determined by the guard chain which remains latched to the door while extended against a spring bias from storage within the stationary jamb-mounted hardware with which the door mounted hardware cooperates.
It is therefore an important object of the present invention to provide a combination door lock and releasable flexible guard element of the foregoing type which is simpler in construction and easier to control.